WEBVTT 0 00:00.360 --> 00:03.330 Now, our next challenge is our press up. 1 00:04.170 --> 00:09.170 And this challenge is going to require you to draw a random walk. 2 00:10.080 --> 00:14.850 Well, it's basically your turtle making random movements North, East, 3 00:14.850 --> 00:19.620 South, or West, each time it progresses by the same distance, 4 00:19.950 --> 00:24.810 but it can at any point choose which direction it wants to go out of the four. 5 00:25.290 --> 00:29.130 And also you can see we've kept the color palette from the previous challenge, 6 00:29.460 --> 00:34.410 and I've just applied it to the random walk so that each time it walks, 7 00:34.470 --> 00:36.090 it's going to pick a different color. 8 00:37.110 --> 00:42.110 Now this random walk is something that's used often in mathematics and other 9 00:42.630 --> 00:43.463 disciplines. 10 00:43.650 --> 00:48.650 So it's a way that can be used to model various real life situations. 11 00:49.380 --> 00:50.700 Like for example 12 00:50.700 --> 00:55.700 the financial status of a gambler or things like the path of a molecule in a 13 00:57.270 --> 01:01.320 liquid or gas or the search path of a foraging animal, 14 01:01.380 --> 01:06.000 and a whole bunch of other things. Take a look at this Wikipedia article 15 01:06.030 --> 01:09.600 which I'll link to and take a look at all the applications 16 01:09.630 --> 01:14.630 including sculpture making or Physics or brain research and a whole lot more. 17 01:16.560 --> 01:17.820 So once you're ready, 18 01:18.030 --> 01:23.030 go ahead and see if you can program your turtle to create a random walk using 19 01:23.310 --> 01:24.210 random colors. 20 01:24.480 --> 01:29.480 And I want you to think about how you can get the thickness of the drawing seen 21 01:30.180 --> 01:33.600 here, so each of the lines is a lot thicker than before. 22 01:34.140 --> 01:39.140 And also see if you can figure out how you can speed up the turtle so that it 23 01:39.330 --> 01:43.050 draws much faster. And everything is of course 24 01:43.050 --> 01:47.430 going to be in the documentation somewhere for you to find. Pause the video and 25 01:47.430 --> 01:48.660 complete the challenge now. 26 01:52.820 --> 01:56.240 Alright. So I'm going to delete all the code from our previous challenge, 27 01:56.510 --> 01:59.150 but I'm going to keep my list of random colors, 28 01:59.450 --> 02:01.610 which I'm going to use for my random walk here. 29 02:02.510 --> 02:04.370 Now I'm going to keep the random import 30 02:04.400 --> 02:08.180 even though it's currently unused because, as you guessed it, our random 31 02:08.190 --> 02:10.760 walk is going to require some randomness. 32 02:11.780 --> 02:16.640 So how do we actually get our robot to move in the four different directions? 33 02:17.090 --> 02:20.240 Well, let's define another list called directions 34 02:20.750 --> 02:24.560 and this is going to have all of the different directions 35 02:24.590 --> 02:27.800 the turtle can face. So we'll start from 0 36 02:28.190 --> 02:32.240 which will be facing East and then 90, 37 02:32.240 --> 02:37.240 which will be facing North, 180 will be West and 270 will be South. 38 02:40.220 --> 02:42.800 So now that we've got these random directions, 39 02:42.830 --> 02:46.160 we can get Tim, our little turtle, to start moving. 40 02:46.610 --> 02:49.940 So every time we're going to move forward by the same distance, 41 02:50.630 --> 02:53.360 and it doesn't really matter how far you move your turtle 42 02:53.780 --> 02:56.480 as long as you set a reasonable number. 43 02:56.750 --> 03:01.750 So I'm just going to choose 30 and then I'm going to get my turtle to turn in a 44 03:02.560 --> 03:03.820 random direction. 45 03:04.330 --> 03:09.330 So I don't want to just use right all the time, so you can use left or right, 46 03:10.390 --> 03:14.710 and pick a random direction from the list. But alternatively, 47 03:14.710 --> 03:18.490 you can actually use this set heading. So for example, 48 03:18.520 --> 03:21.100 we can set it to those four directions. 49 03:21.640 --> 03:26.560 All we have to do is call setheading and then pass in one of those angles. 50 03:27.250 --> 03:28.210 That's what we're going to do here. 51 03:28.240 --> 03:33.240 We're going to use the random module and the random choice method to pick a 52 03:34.900 --> 03:36.340 random direction. 53 03:37.660 --> 03:42.660 So now this robot is going to move forwards and then it's going to turn a random 54 03:43.420 --> 03:47.230 direction. But of course, we want this to loop a few times. 55 03:47.320 --> 03:50.350 So let's say that we get it to loop 200 times. 56 03:50.410 --> 03:53.740 I think that should be enough to draw a decent sized image. 57 03:54.400 --> 03:58.600 Let's set the range to maybe 200 times for this loop to run. 58 03:58.930 --> 04:01.480 I think that should get us a decent image. Now, 59 04:01.480 --> 04:05.770 if you chose 300 or 500 or whatever the number, it doesn't matter. 60 04:06.190 --> 04:10.240 As long as you can get a decent image on screen, then it's perfectly fine. 61 04:10.960 --> 04:14.170 So we've now satisfied the basic constraints of a random walk 62 04:14.350 --> 04:18.130 and you can see our turtle is now wandering around this alleyway, 63 04:18.160 --> 04:21.820 completely aimlessly and modeling a real life process, 64 04:21.880 --> 04:23.650 like an animal that's hunting for food. 65 04:25.120 --> 04:27.370 Now let's implement the next part of this. 66 04:27.490 --> 04:32.490 Let's go ahead and change our code so that it generates a random color for each 67 04:32.560 --> 04:33.393 step. 68 04:33.850 --> 04:37.870 That's pretty simple cause we did it before in the last lesson. 69 04:38.200 --> 04:42.640 So we're going to get Tim to change his color and we're going to use the random 70 04:42.640 --> 04:43.473 module 71 04:45.100 --> 04:50.100 and the choice method to pick from all the colors that we've already got in this 72 04:50.800 --> 04:55.390 list here. Now that it's pretty much random colors, 73 04:55.540 --> 04:58.510 random walking, the next thing we want to do 74 04:58.780 --> 05:03.780 if you saw my demo of it is we want to make each of the lines a bit thicker. 75 05:04.570 --> 05:09.040 So how do we do that? Well, we have to head back to the documentation. 76 05:09.670 --> 05:12.370 So it's probably going to be one of these methods. 77 05:12.760 --> 05:15.100 And if we just read through the names of the methods, 78 05:15.400 --> 05:20.400 they should give us a bit of an indication of which one might be the one that we 79 05:20.680 --> 05:21.513 want. 80 05:22.540 --> 05:26.020 If we take a look at the drawing control for our pen, 81 05:26.290 --> 05:31.290 you can see there's a method called pen size and you can call this either pen 82 05:31.480 --> 05:35.350 size or width, but it does the same thing. Essentially 83 05:35.350 --> 05:39.130 it just sets the size of the pen which the turtle draws with. 84 05:40.900 --> 05:45.070 If we set the pen size to something a little bit wider, 85 05:47.380 --> 05:50.710 say maybe 15 in width, 86 05:51.370 --> 05:53.830 then you can see when our turtle draws, 87 05:53.890 --> 05:57.130 it's now a lot wider and it's a lot easier to 88 05:57.260 --> 05:59.420 see what it's doing. Now, 89 05:59.420 --> 06:03.290 the final trick I want to show you is how you can speed up the turtle's 90 06:03.290 --> 06:07.100 animation. So if I was to wait for it to finish drawing here, 91 06:07.100 --> 06:08.630 that's perfectly possible, 92 06:08.840 --> 06:13.840 but I can also speed it up by tapping into the speed method for turtle. 93 06:15.020 --> 06:20.020 And I can either specify this speed as an integer or as a string. 94 06:22.070 --> 06:25.940 So the strings are fastest, fast, normal, slow, slowest, 95 06:26.240 --> 06:30.950 and this determines the animation speed of the turtle as it draws. 96 06:31.370 --> 06:35.900 So I'm going to go for fastest so we can say tim. 97 06:35.900 --> 06:40.340 speed. And we'll put in that string, fastest. 98 06:41.480 --> 06:46.040 And now when we run it, you can see it animates way faster 99 06:46.400 --> 06:48.500 and it's drawing at the speed of light. 100 06:49.070 --> 06:52.580 Our little turtle is completely going nuts, 101 06:53.780 --> 06:58.610 but this means that it will take much less time to complete our 200 cycles as 102 06:58.630 --> 06:59.620 we requested. 103 07:00.970 --> 07:04.870 So I hope you enjoyed this lesson and you managed to get your turtle to do a random 104 07:04.870 --> 07:06.130 walk. Now, 105 07:06.250 --> 07:09.760 many of you would have done this challenge and you might've thought, wouldn't it 106 07:09.760 --> 07:14.760 be nice if I could generate a completely random color rather than just selecting 107 07:15.070 --> 07:17.800 a random one from this list? Well, 108 07:17.920 --> 07:21.520 we can do that and I'll show you how in the next lesson.